1. Field of the Invention
This disclosure relates in general to network delivery of data and, but not by way of limitation, to transfer of content in unique ways.
2. Background
Traditional data delivery using the Internet falls into two broad categories, namely, traditional origin download and end user originated download. Either type of download can be used for content delivery such as file uploads and downloads or streaming delivery. In a traditional origin download, a centralized server (such as an origin server), a traditional content delivery network or a traditional cache operates as a source of the content for the end users. In a user originated download, one end user sources content to another end user.
In early user originated download systems, often referred to as first-generation peer-to-peer (P2P) content delivery systems, when an individual end user seeks to find content available from its peers, the end user logs into a central indexing server. The requesting end user consults a tracker function within a central indexing server that serves as a file directory of content available from sourcing end users. Once a sourcing end user offering the requested content is identified, the actual content transfer occurs directly between the requesting and sourcing end users.
User originated download is controversial for many reasons. There is a perception that user originated download fosters copyright theft. In addition, internet service providers (ISPs) dislike user originated downloading because of the high level of resource utilization it imposes on the ISP system and the difficulties associated with managing an increased flow of data. Not withstanding these issues, user originated downloads continue to become more popular among end users to support applications such as Internet telephony, file/stream transfer and Internet television.
Many ISPs have attempted to regain control over the resource utilization of their network infrastructure by attempting to identify and regulate user originated downloads. Some have resorted to traffic throttling or shaping to slow down or eliminate resource utilization.
However, second-generation user originated download systems, also known as decentralized P2P systems, have eliminated the need for a central server. In such a system, peers send search queries to other peers. If a peer cannot service a request, it forwards the query to other peers until the requested information is found. When the information is found, the initiating peer receives the download directly from the peer with the information. Using these and other techniques, the second-generation user originated download systems seek to evade the network restrictions by impeding the ability of the ISP to detect P2P traffic as there is no central indexing server.
Third-generation hybrid user originated systems, also known as hybrid P2P systems, operate between a centralized directory structure and a distributed structure. The networks use super nodes which act as mini central servers to keep the network distributed while reducing the time required to identify the holder of requested content. These super nodes are typically unaware that they have been selected to act as such. Often, the third-generation user originated download systems also seek to evade the network restrictions by impeding the ability of the ISP to detect the P2P traffic.
There is a long tail theory that suggests obscure content is difficult to deliver to end users efficiently. Caches are efficient at delivery of commonly requested items, but rarely store obscure content. Often obscure content must be sourced from the origin server if still available. Where an end user has the obscure content, depending on the delivery suitability of that user, user originated download can serve to source the content to another end user, without going back to the origin server. This type of efficient transfer benefits both the end user and the ISP.